Download New Product Current Regulators Simplify the Driving of LEDs

Issue Number │001
July 2015
New Product
Announcement
BCR420U
BCR421U
Current Regulators Simplify the Driving of LEDs
BCR420U and BCR421U
constant current regulators
provide a simple means of
driving low-power LED strings.
Target applications are those
that benefit from the improved
efficiency, flexibility and longer
life offered by LEDs as an
emerging lighting source.
Supporting adjustable currents
from 10mA to 350mA allows for
platform designs based on a
single device to be used across
multiple LED strip applications,
considerably easing a
manufacturer’s overall
qualification process. These
LED drivers also enhance
system reliability as the
monolithic integration of a
transistor, diodes and resistors
both simplify system design
and reduce component count.
The 40V maximum input rating
ensures sufficient headroom for
transient supply voltages and
allows for LED short failures on
long strings. With its low-side
driver configuration, BCR421U
has the added feature of an
enable function that can adjust
the light output level using a
PWM input signal.
The Diodes’ Advantage
BCR420U & BCR421U are Constant Current Regulators (CCR) for Driving
Low- Power LED Strings by Using an NPN Emitter-Follower with an Emitter
Resistor to Limit Current.
 10mA to 350mA Current Range
Adjustable CCR enables platform designs based on a single device to use
across multiple LED strip applications – easing manufacturer’s overall
qualification process.
 Increased Reliability
Monolithically integrating a transistor, diodes and resistors: both simplifies the
system by reducing component count and increases overall reliability.
 1.4 to 40V Supply Voltage
Low -voltage overhead with sufficient headroom for overvoltage conditions such
as LEDs failing short.
 Negative Temperature Coefficient
Self-protects and allows current sharing between parallel CCRs.
 BCR421U with PWM
Enables function that can adjust the light output level by PWM up to 10kHz.
Applications
Low Power LED Strings:
 Mood lighting
 Emergency lighting strips
 Advertising signage



Retail refrigeration
Vending machines
Architectural lighting strips
www.diodes.com
Issue Number │001
July 2015
New Product
Announcement
BCR420U
BCR421U
BCR42xU Family
Orderable
Part Number
Configuration
PWM
from µC
Input
Voltage
Fixed
Current
Adjustable
Current
Package
BCR420UW6-7
NPN Low-side
No
1.4 to 40V
10mA
10 to 350mA
SOT26 (SC74)
BCR421UW6-7
NPN Low-side
Yes
1.4 to 40V
10mA
10 to 350mA
SOT26 (SC74)
Examples of Application Circuits
Low-side control of an LED string with adjustable
current by varying the external resistor (optional).
Dimming of the LED string to adjust the light output; this
is PWM controlled from a microcontroller by toggling the
enable pin on the BCR421U.
Cross Reference
In SOT26 (SC74) package these are pin-compatible and exact equivalents to:
Part
Diodes Inc
Orderable
Part Number
Infineon
Orderable
Part Number
Infineon
Orderable
Part Number (*)
Package
BCR420U
BCR420UW6-7
BCR420UE6327HTSA1
BCR320UE6327HTSA1
SOT26 (SC74)
BCR421U
BCR421UW6-7
BCR421UE6327HTSA1
BCR321UE6327HTSA1
SOT26 (SC74)
*BCR320U & 321U are low voltage versions of the BCR420U & 421U.
www.diodes.com